Silhouettes Gallery

Northern lights

Northern lights. The Northern Lights are created as electrically charged particles from the Solar wind are pulled in toward the magnetic poles by the Earth's magnetic field. As these particles collide with the atoms of gas in the ionosphere about 80km above the ground, they give the atoms energy and they become excited'. The atoms spontaneously release this energy in discrete amounts, resulting in particular colours of light being emitted. Photographed in the Swedish Arctic

© Jeremy Walker

Silhouettes from the Somme by H. L. Oakley

Various scenes on the Somme cut by famous silhouette artist, Captain H. L. Oakley showing the work to be done when pursuing the retreating Germans. A party of Pioneers are mending the roads, a cavalry squadron (the Australian Light Horse) return from close contact with the enemy, and the Royal Engineers make roads and rivers passable. Progress is reported by the liaison officers attached, and communication is supplied by Royal Engineers signallers. Date: 1918

© Illustrated London News Ltd/Mary Evans

Mauna Kea telescopes and Milky Way

Mauna Kea telescopes and Milky Way. Silhouetted against a sunset glow are the Subaru Telescope (far left), the Keck I and II telescopes (centre left and centre), and NASA's Infrared Telescope Facility (far right). These telescopes are located on the summit of the Mauna Kea volcano, on the Pacific island of Hawaii, USA. The starry band of the Milky Way and its scattered nebulae (dark areas) dominates the night sky

© DAVID NUNUK/SCIENCE PHOTO LIBRARY